I had the same issue. It will not let me login and I changed the password many times.
The apparent cause is Microsoft thinks there has been fraud or your account or it was hacked. They do not tell you this but just block your account.
The only way around Microsoft is to add an alias to your account. Look for directions on how to do this. you will never be able to long into your account except through your alias.
When you log in though your new alias, you can see all of your messages and people can still send messages to your old name, but for all time moving forward you need to only log into your alias